Diamond drill bit



c. E. CARPENTER ET AL 2, 4,617

'DIAMONDDRILL BIT Filed April 1, 1959 BY /@%MH ATTORNEYS.

' so as to eliminate the ship of parts and their Patented Dec. 2, 1941 2,264,617 DIAMOND DRILL BIT and Raymond C. Lynch,

Clarence E. Carpenter Seattle,

Wash.

Application April 1, 1939, Serial No. 265,579

Claims. crass-s1 This invention relates to rotary drills as used for the formation of holes in rock, granite, stone,-

and other hard materials, for the purpose of testing or blasting, and it has reference more particularly to improvements in drill bits of that type known generally in trade as diamond drills, and which are of that particular kind designed to cut away all of the material within the circumference of the face of the bit, thus to eliminate the necessity for any provision of means for the passage of a core; the present invention being an advancement in many respects over the drill bit that is disclosed in our copending application, filed on October 20, 1938, under Serial No. 235,978. It is the principal object of this invention to provide a high speed, rotary, face bit having a central, concave recessed surface located coaxial of the bit, and surrounded by a convex surface, and wherein both the concave and the convex surfaces have diamond cutters so set therein that the entire area of the surface acted on by the bit will be cut away and ground up for removal by an outflow of water that is delivered under pressure through the drill rod to the face of the bit for lubrication of the cutters.

Another object of the present inventionresides in the provision of an outlet of novel form and of special location in the face of the bit for the discharge of the water to the drill face and which outlet, by reason of its shape and disposition, and incident to the high speed of rotation of the bit,

in Fig. 2, and an in operates as a pump that efiects a-forced eleanout of the sludge resulting-from the drilling operation.

It is also an object of this invention to provide a novel overlapping arrangement of the diamond cutters at the apex of the recessed drill face formation of a core and thus to relieve central pressure against the bit; also, by beveling the end surfaces of the bit in a novel manner to obtain the most advantageous results from the standpoint of adding life to the cutters and especially eliminating excessive wear on those which travel the fastest and the greater distance.

Still other objects of the invention reside in the various details of construction, the relationmode of operation as will hereinafter be fully described.

In accomplishing these and other objects of the invention, we have provided the improved details of construction, the preferred forms of which are illustrated ing, whereinthe accompany drawmain, circular in cross section,

Fig. l is a side as functionally applied to a drill rod.

Fig. 2 is an enlarged, sectional view of the bit taken along its axial plane.

Fig. 3 is an end, or face view of the bit.

Fig. 4 is a detail in section of the bit, with the diamond cutters omitted for better illustration, wherein the preferred angles given the various surfaces are indicated.

Fig. 5 is an enlarged sectional detail, particularly illustrating the setting of the diamond cuttersat the apex of the face recess.

Referring more in detail to the drawing- The present drill bit is designated in its entirety by reference numeral l0, and' it comprises ahead or drilling portion proper, ll, comprising substantially the lower end half of the bit as seen i riorly threaded neck or shank portion l2, comprising the upper half portion and whereby the bit may be mounted for a drilling operation on the end of an externally threaded tubular drill rod such as designated at l3 in Fig. 1.

The bit, as seen best in Fig; 2, is hollow, there by providing an internal chamber M which has direct communication with the lower end of the drill rod; it being understood that the latter serves as the mediacy through which water is delivered under pressure to the bit to lubricate the cutters, and to wash away the sludge as the mate rial acted on is ground up by the cutters under the rotary action of the head. The water supplied to the head through pipe I3 is delivered to the cutting face from the chamber l4 through an outlet or opening I5 which will presently be described in detail. I

The head portion ll of the drill bit is, in the as is also the neck or shank portion, and it will be observed'that the neck portion is of slightly lesser diameter than the head portion, thus forming an upwardly facing, annular shoulder l6 about the bit. This reduction of the diameter of the neck por-' tion of the tool provides more clearance between 45 the wall of the neck hole than is provided insures an easy outflow of water after it has passed the shoulder.

Before going into a detailed description of the bit, it will be explained that there are several very important advantages in not being required to take a core in-a. boring or drilling operation,

and surface ofthe drilled where a core is not required to be taken.

Itwillbe view of the present drill bit,

about the head portion and understood that any hole, even small, will allow a core to pass through into the central water passage of the bit, which passage is under water pressure while drilling is going on and the flow of water is toward the face of the bit. This small core, coming up through the center hole, naturally breaks up. The result is that the water discharge holes of the bit will become clogged, and proper lubrication of the face of the bit thus prevented, with the result that the bit becomes burned and considerable loss of time in correcting the damage and replacing the bit is experienced.

Referring more in detail to the details of formation of the working face of the bit, it will be noted that it is provided centrally and coaxially of the bit, with a conically tapered, concave recess l8, the walls of which recess in the preferred design shown, are inclined at an angle of approximately 48 with respect to the axis of the bit, as will be understood best by reference to Fig. 4. Immediately surrounding this central recess I8 is an annular surface i 9 which slopes conically at an angle of approximately 78 with respect to the axial line of the bit, thus forming an angle of 30 with reference to an extended surface of the centralrecess. The annular surface I9 merges into the wall surface of recess l8 along a circular line designated at 20 in Fig. 3 that is concentric of the bit, and which lies in a plane that is perpendicular to the axis of the bit. This circle, identified by reference numeral 20, has a diameter that is approximately one-half the full diameter of the drill head.

Surrounding the recess [8 and the concave surface IS, the working face is of convex formation ingeneral, comprising a succession of annular, conically sloping surfaces of different and successively increased degrees from the surface of smaller diameter to the outside of the head. Referring in particular to Fig. 4, these several annular surfaces are designated by reference numerals 22, 23, 2! and 25.

The annular, conically formed surface 22 slopes at an angle of 60 with reference to the axial line of the bit, and is surrounded by the conically formed surface 23 which slopes at an angle of 45 relative to the-bit axis and merges into the surface 22 along a circular line designated at 26. Likewise, the annular, conical surface 24 which is formed at an angle of 30 with reference to the axial line of the bit, merges along a circular line 21 into the outer conical surface 25, and the latter slopes at an angle of 15 with reference to the bit axis and merges into the circumferential surface of the bit into a plane that is perpendicular to the axis. The points of mergence of the various surfaces are designated in Fig. 4 by primed reference numerals which correspond to the reference numerals applied to the circles in Fig. 3.

It-is to be understood that the angles of slope herein indicated and stated, are those now preferred, but might be varied within certain reasonable limits without in any way departing from the spirit ofthe invention. Also, it is to be understood that the number of distinct annular surfaces might vary as desired or found necessary for producing the best results in bits of varying diameters.

As will be observed by reference to Fig. 2 of the drawing, diamond cutters 30 are closely set in the end surfaces of the bit, to extend somewhat above the line of mergence of the surface 25 into the outer surface of the bit. The location and setting of these diamond cutters in the various surfaces is of importance, particularly as it applies to those located near the apex of the center recess. Heretofore, it has been contended that it is impractical to locate diamond ,cutters near the axial center, or apex of a conical recess, and for that reason, bits employing such a recess have most generally been provided with a central hole for the passage of a core, and the diamond .cutters have been set closely around the hole to cut out the core.

In the present instance, we set diamond cutters quite close to the apex of the recess and have chosen those of proper form and have set them in such manner that they will intersect the axial line. This method of setting the diamonds has proven to be very advantageous and we have found also that these diamonds do not wear as rapidly as those farther removed from the apex.

The present method also contemplates the use of several small diamonds set near the apex of the recess and pointing toward the center, asin Fig. 5, to such extent that the center portion of the surface acted on will be completely cut away. There is also, in this bit, a large number of small diamonds set in the recess in a line that describes the path of a scroll, as designated at s in Fig. 3, and which scroll continues to the full diameter of the face of the bit; each diamond being required to take only a small amount of pressure and to do only a small amount of cutting. Thus, the diamond loss will be materially less and the rate of advancement of the bit will be materially increased.

Referring now to the convex portion of the bit surrounding the central recess, it will be observed that the two upper surfaces 24 and 25 are of such slope that they permit the diamond cutters to be set in such manner as to have a reaming effect; that is, these diamonds can be so positioned that they will overlap each other in their cut, and none of the diamonds will be required to take more than a very small amount of work.

Furthermore, since the highest, or gauge row of diamonds, is required to take such a light out and removes such a small amount of material from the hole, these highly important cutters will last much longer than those set in any other type of bit face. In fact, the wear is so slight that thegauge size of the bore will be maintained for the life of the bit and no difficulty is experienced when a new bit is applied to the bore for continuation of an operation. It has been found impossible to get the same results with a reduced or curved surface, regardless of the shape given the bit. Also by reason of there being a large number of diamonds in the gauge row and since the amount of work done by each is so slight, and their life thus lengthened to such an extent, the use of a reaming shell, to maintain hole size as is ordinarily used, may well be eliminated.

The two lower, annular surfaces 22 and 23 are constructed in this way to give projected area to the bit. This also applies to the two upper surfaces; it being obvious that the greater the of work, a greater rate of advance in inches per minute can be obtained than with a bit having fewer diamonds.

The fact that the angles of slope ofthese several surfaces are graduated at 15, sharp corners, as are found in a square face bit, are eliminated, and since the diamonds are set at 90- with the surfaces and each diamond completely surrounded by holding and projecting metal, except to expose the fine cutting edges,

correctly determined as must also its length, measured from the discharge at the end of the bit. The :water way or passage IS in plan, as noted in Fig. 3, is in the form of a slot, and is curved about a center point that is eccentric of the bit, using aradius greater in length than any circle of the bit; such a center being designated at c in Fig. 3. The location and curvature of this passage IS with reference to the direction of rotation designated by the arrow in Fig. 3, is designed to effect a centrifugal action, while the bit is in operation, thus drawing the heavy waterborne sludge to the outside of the bit into a stream of uncontaminated water which is always flowing through thewaterway. This waterway must be located at a distance suificiently removed from the apex of the cone that it will not interfere with the proper placing of the diamond cutters near the apex.

It is also of importance that'the opening l5 extend in the direction of rotation well beyond a line through the center 0 and the axis of the bit. In fact, the forward end portion of the opening should extend beyond indicated line to anextent approximately equal to the width of the opening; such a distance being designated by the line d in Fig. 3.

Since the operating speed of such bits is from 3,000 to 5,000 revolutions per minute, it is apparent that the waterway must be so designed as to effectively and properly lubricate and clean the bit and the present design has been arrived at after much experimenting along this line, and

has proven entirely satisfactory.

The outside of the bit head immediately above the upper or gauge row of diamond cutters, is machined to the same size as the last row of diamonds; this size being carried up far enough along the side of the bit to insure an arrestin or choking action to properly retain the wash water. This also gives added protection to the last row of diamonds. The reason for desiring the mentioned choking of the water is to insure that a sufiicient amount will be retained over the cutting face of the bit. The cuttings from the bit, in this instance, are carried away by the wash water thrdugh a curved water way 30 that extends up the outside of the convex surface and along the side of the bit; this waterway being large enough to convey the cuttings, yet not large enough to cause any material drop in be extended spirally, or straight as in Fig. 2, as desired.

The first annular surface in the concave portion of the bit is sloped at 12 with reference to a plane perpendicular to the axis of the bit. This angular surface I9, meeting the sloping surface 22, provides what might be called a point, which greatly facilitates starting the bit on a face of rock, and overcomes the tendency to walk" around as does a flat faced bit.

Having thus described our invention, what we claim as new therein and desire to secure by Letters Patent is:

1. A rotary drill bit adapted for functional mounting on a tubular drill rod and having a concave recess centrally in its working face, and a convex surface surrounding the said concave recess; 'said bit being formed with an internal chamber, adapted to communicate with the channel of the drill rod and an outlet therefrom to the face of the bit, and cutters mounted in the face of the recess and in the surrounding concave surface, with those cutters adjacent the apex of the recess set in a manner to intersect the axial line of the bit.

2. In a rotary drill bit of the character disclosed, a head portion formed in its working face, coaxial of the bit, with a conical recess; and cutters set in the surface of the recess with those adjacent the apex mounted in a manner to intersect the 'axial line.

3. A rotary drill bit adapted for threaded mounting on a hollow drill rod and having a concave recess coaxially of its working face, and a convex surface surrounding the said concave recess; said bit being formed with an internal chamber adapted. for communication with the channel of the hollow drill rod and with an outlet from the chamber to the working face of the bit, and with a relief channel extending from the face of the bit and upwardly therealong for outflow of wash water to the drilled hole above the bit; said concave recess having a diameter substantially half that of the bit and said outlet from the chamber opening to the face of the bit within the said recess but removed from the apex; and cutters set substantially close together in the face of said recess and in the surrounding convex surface, with those cutters adjacent the apex of the recess set to intersect the axial line.

4. A rotary drill bit as recited in claim 3 where- 'in the outlet from said chamber opens to the working face of the bit within the concave recess and removed from the apex, and extend arcuately acrws the face about a center that is located slightly outside the bit and substantially diametrically opposite the location of said outlet; and wherein the outer end of said outlet communicates with the said relief channel.

5. A rotary drill bit comprising a head portion of circular cross section anda mounting shank of slightly reduced diameter adapted for mount- .the face of the recess and'in the surrounding surfaces, with those at the apex of the, recess water pressure under the face of the bit. It may I intersecting the axial line, and those in the convex surfaces of greatest pitch set to produce a reaming efiect on the drilled hole: said head having an internal chamber in communication with the channel of the drill rod and an outlet to the face of the head opening into the recess but removed from the apex and arcuately curved about a center that is outside the head and diametrically opposite the opening, and there being a. relief channel in the face of the head leading from the outlet to the portion of reduced diameter of the bit.

CLARENCE E. CARPENTER. RAYMOND C. LYNCH. 

